Ultrastructural evidence suggesting an immunomodulatory activity of oral retinoid.

The effects of the aromatic retinoid Ro 10-93 59 on the fine structure of psoriatic dermis were investigated by electron microscopy in five patients after 1, 2, and 3 weeks of treatment (1 mg 'kg' day). Our findings show that aromatic retinoid, additionally to its epidermal effects, exerts a distinct influence on dermal components in psoriasis. Ultra structural evidence is provided suggesting that this drug stimulates lymphocytes and monocytes, promoting their differentiation into Sézary-like lymphocytic cells, activated macrophages and dermal Langerhans cells. The appearance of these immunocompetent cell lines may modulate the cell-mediated immune response in psoriasis, obviously reflecting a pharmacological action of the drug additional to its definite influence on epidermal keratinization. [ABSTRACT FROM AUTHOR]